Soil Testing for Gardens and Forage

Transcription

1 Soil Testing for Gardens and Forage Ravalli County Extension Hamilton, March 20, 2018 Clain Jones, Extension Soil Fertility Specialist ,

2 Why should land owners know something about soils? For healthy plants, tasty vegetables, good forage yields, and cover for livestock and wildlife To protect the environment For efficient use of resources (water, fertilizer, $)

3 Today s topics Present what a soil test tells you Soil nutrients Soil properties Explain limitations, to know which properties you can influence Provide fertilizer guidelines and example calculation for gardens and forage Compare fertilizer sources Consider options other than soil tests to guide soil nutrient management

4 Hands-on is the best way to learn, but we ll use clickers because. 1. I just had my nails done 2. Clicker training isn t just for dogs 3. There isn t enough dirt on the floor to get a good soil sample 33% 33% 33% Response Counter

5 Soil test To identify nutrient deficiency or imbalance To help calculate fertilizer rates Can increase yield and/or save on fertilizer costs, and decrease environmental risks Best done in early spring, but not when soil is wet, therefore in our climate perhaps best done in late fall See publications listed at end for details on how-to

6 What to look for on a soil test report? Factors affecting plant health and production Factor Value Impact/consider Nutrient content Soil organic matter Soil ph Soluble salts (EC) Soil texture and CEC Nutrient dependent 1 (%) Too little = hungry plants, too much = contaminate water, burn plants Minimize bare soil, increase N, add legumes > 3 (%) Little need for extra N on pasture < 5 Poor seedling establishment < 6 Poor legume nodulation > 8.3 Nutrients tied up, possibly high Na > 4 (mmhos/cm) Too saline, water stress, nutrient imbalance Water and nutrient holding capacity

7 Soil test report for Stevensville location: 3 different fields Note difference in: SOM ph and CEC N P, K Nitrate-N PHOS.

8 Soil test report for Stevensville location To determine N rate you need: 1. Yield goal 2. Soil sample depth to convert ppm to lb N/acre (ppm x 2 x actual depth in inches / 6) Nitrate-N Phosph. P rate: MSU guidelines are based on Olsen P. Bray works in ph < 7.3, Olsen works ph > 6.

9 How do I know what to add to my soil??? Six questions to ask yourself before you add fertilizer 1. Which elements do I need? (N, P, K, S, Ca) 2. How much do I apply? 3. What type of material do I use? 4. Which application method is best? 5. When is the best time to apply it? 6. Will I get a return ($ or environmental) on my investment? A. Miller

10 How much fertilizer do I need to apply? Estimate the amount of fertilizer needed based on soil test results, crop needs and area to receive fertilizer Most fertilizer recommendations are in lb/1,000 sq. ft. in top 6 for gardens, or lb/acre in top 2 ft. for N, and top 6 for P and K on croplands If lab doesn t provide a recommendation or is from another state, MSU bulletins MT200702AG, 03AG,and 05AG provide guidelines and example calculations

11 For gardens, in top 6, see The Soil Scoop or MT200705AG Soil Test Organic Matter (%) Nitrate - N < > 3.0 lbs /acre lbs/1000 sq.ft. < > Olsen P (ppm) < > 16 lb P 2 O 5 /1000 sq. ft K (ppm) < >250 lb K 2 O/1000 sq. ft

12 Fertilizing forage in MT Focus of N or P&K depends on % legume in stand Fertilizing with nutrients other than N favors legumes over grass

13 N fertilizer guidelines for alfalfa and grass in MT In Forages: Nitrogen Management Soil Scoop and MSU EB0216 Alfalfa/Grass Yield Potential 80/20 60/40 40/60 20/80 0/100 (ton/acre) Available N Need (lb/acre)* * Fertilizer N = Available N Need Soil nitrate-n in top 2

14 P guidelines for alfalfa and grass based on soil analysis In Forages: P, K, S, & micros Soil Scoop and MSU EB0217 Olsen P Soil Test Level (ppm) Crop P Fertilizer Rate (lb P 2 O 5 /acre) Alfalfa Alfalfa/grass (50/50) Grass If soil test is above 16 ppm then consider using removal rate (10 to 11 lb P 2 O 5 /ton)

15 K guidelines for alfalfa and grass based on soil analysis In Forages: P, K, S, & micros Soil Scoop and MSU EB0217 K Soil Test Level (ppm) Crop K Fertilizer Rate (lb K 2 O/acre) Alfalfa Alfalfa/grass (50/50) Grass If soil test is above 250 ppm then consider using removal rate 38 lb K 2 O/ton grass, 53 lb/ton alfalfa

16 Your turn OM % Nitrate N lb/ac P ppm K ppm ph Test Market gardeners: Using these data and Tables 1 and 2 from Feeding the Vegetable Garden soil scoop, how much N, P, and K are required for this garden? Forage producers: Using this data and tables from the 2 forage soil scoops, how much N, P, and K are required to grow 3 ton/acre of grass?

17 N, P, and K rates? OM % Nitrate N lb/ac P ppm K ppm ph Test Nutrient N P 2 O 5 K 2 O Garden (lb/1000 sq ft) Forage (lb/acre) 3 60* 2 ~ *Need to subtract out soil nitrate-n from available N need

18 Sulfur tissue tests and visual symptoms are better than soil tests Standard sulfate soil test too unreliable Better to use visual symptoms (yellow or light green upper leaves) tissue test critical values provided by lab or our documents Last year production performance Wheat, image from IPNI

19 S influence on annual forage nitrate content: western Montana Westcott unpub. data

20 Which of the following nutrients is NOT reliably managed based on soil test values? 25% 25% 25% 25% A. N B. P C. K D. S N is mobile, yearly variation, base on yield goal and soil tests P and K more stable, base on soil tests S mobile, base on field history and deficiency symptoms Response Counter

21 Questions? On to special considerations for forages

22 Why not use high N to boost forage yield? Favors grasses and weeds in mixed stands Trade-off between yield and forage nitrate Potential protein decrease Possible losses to water Bromegrass, Vimy, Alberta 12 May-Sept rainfall Penny et al and MT200505AG

23 Diminishing return of increasing N - on irrigated western wheatgrass, Blaine Co. ton/acre 100 lb N/acre 50 lb N/acre Long-term cumulative effect by single fall broadcast N on dryland introduced rhizomatous grasses. Introduced > native response, rhizomatous > bunch response Lorbeer et al. 1994, Jacobsen et al.1996, Havre

24 Split app may increase total yield, improves distribution over season Early spring alone, or split btwn. early spring and after 1 st, or 1 st and 2 nd cutting

25 Challenges to high N use efficiency in perennial systems, and N options Urea needs 0.5 water or tillage to incorporate N Plant residue intercepts fertilizer increases volatilization can tie up N Surface band liquid N Polymer coated N works for extended forage season or late cutting Legume in pasture mix or legume cover crop in market gardens may be best N source Malhi et al. 2002, Eckville, Alberta 17.5 avg annual and 10.5 May-Aug precip

26 Fertilization strategy If a field containing < 75% legumes will be rotated into a different crop soon, consider N for immediate gain If goal is low input, long-term sustainable production rather than prime quality hay, adequate P and K are key and cheaper than re- or interseeding If you need to buy hay or rent pasture, you should consider fertilizing for long term benefit On dryland grasses, a single 50 lb N/acre was more economical over 5 years than a single 100 lb N/acre. More is not always most economical, and need to look at long term (Jacobsen et al., 1996).

27 P and K fertilization strategy Is a single lb P 2 O 5 /ac on dryland alfalfa as good as the same amount divided over 5 annual applications? 50% 50% A. Yes B. No vs. A large application produced similar yield, protein and profit as 5 small annual applications (central Alberta, Malhi et al. 2001). Immobile nutrients can be banked know soil test levels and if low, build up P and K when prices low Response Counter

28 Questions? On to conventional vs organic matter

29 Conventional/chemical fertilizers No carbon Easy to store Higher nutrient concentration Custom formulated Easy to use but calibrate your equipment Liquid and solid Coated specialty products reduce leaching, volatilization, runoff losses.

30 Organic Fertilizers Bulkier Nutrient content low Nutrient content difficult to quantify Supply organic matter and other soil quality benefits General % of dry weight Type N P 2 O 5 K 2 O Manure compost Garden waste

31 Approximately how much total N, P, and K does 1 of manure compost supply? N P 2 O 5 K 2 O lbs/1000 sq. ft. Removed annually Added by 1 manure Added by 1 manure To add 5 lb N/1000 sq. ft. takes approx. 500 lb manure compost or 11 ton/acre 1. Morris, Ping, and Durgy. University of Connecticut. 50% 50% Response Counter

32 X Conventional Do not apply on snow, before heavy rains or snowmelt Apply and incorporate (nitrogen) shortly before plants take off in the spring Broadcast N fertilizer needs to be incorporated by tillage or ½ water event Provide additional N mid-season if needed Specialty slow release Incorporate and apply early in growing season or use blend of quickly available source and slow release Application considerations

33 Application considerations: organic material Incorporate in the fall or spread composted in the spring, once ground thaws, but before growth starts Do not apply on snow or frozen ground N can be tied up due to high C Manure: Creates rapid buildup of P and K recall soil test example. If fertilizing to meet N needs, feed to P and K demands and use legumes or source such as blood meal to supply N Consider the salt, weed seed and pathogen content Herbicide residual; SOM has huge CEC, CEC holds onto herbicides - know your source!

34 Questions? On to other factors that influence soil nutrient management

35 What else from a soil test? Published rates are developed for entire state and sometimes based on neighbor state s trials. They are likely not accurate for a particular field.

36 Which soil property does NOT influence nutrient availability? 20% 20% 20% 20% 20% A. Texture/surface area B. ph C. CEC (cation exchange capacity = the parking spaces in soil for nutrients) D. SOM (soil organic matter) E. Color Response Counter

37 Soil texture Water and nutrient holding capacity Sand: large pore space, low surface area = low water or nutrient holding capacity Clay: small pore space, large surface area, often negative charge on surface = holds water and nutrients tight Particle and pore size Ideal is loam to clay loam approx. equal parts of sand, silt, clay

38 Texture Effects on Soil Properties Drainage Water holding capacity Aeration CEC Sand excellent poor excellent low Silt good good good medium Clay poor excellent poor high Soils with large surface areas, such as clay and organic matter, have more cation exchange capacity and surface area and therefore are generally more fertile.

39 Soil ph which is true? 1. Has no influence on nutrient availability 2. Is difficult to alter 3. Most vegetables prefer ph > Legumes prefer ph < 6 to fix N 25% 25% 25% 25% Response Counter Soils

40 What are surface horizon ph values in this region? There are known areas in western Montana with top 6 ph < 5.5 Ex: Near Hamilton and Plains, Other areas have ph levels near 8.0. ph Map courtesy of NRCS

41 ph affects soil nutrient availability Low ph, acidic soils may limit N, Ca, Mg, Mo because they don t stick tight and can leach away (Fe) or form minerals (P) High ph, alkaline calcareous soils may limit P, Fe, Mn, B, Cu, Zn because they stick tight to the soil, plant can t get them

42 What is the best option to lower ph in highly calcareous soils? 17% 17% 17% 17% 17% 17% A. Add elemental sulfur (S) B. Add gypsum (CaSO 4 ) C. Add pine needles D. No reasonable option to lower significantly and QUICKLY on LARGE scale E. Use ammonia based N fertilizers (e.g., urea) F. Plant legumes Response Counter

43 Adding elemental sulfur 8.2 April 5 months later Consequences? Costs? Soil ph AgVise Laboratories Sulfur Added (lb/1000 sq. ft.) 10,000 lb/acre

44 What might happen if you add 230 lbs S/1000 sq. ft.? A. You spend $366/1000 sq ft B. Your soil ph will drop by at least 1.5 units C. Soil S levels will remain well below toxic D. Soil salt levels will improve 25% 25% 25% 25% Response Counter Same study site added 115 lbs gypsum /1000 sq. ft. with no change in soil ph

45 Acid soils have many negative impacts Herbicide persistence (Raeder et al., 2015) Damaging to rhizobia (N-fixing by legumes) Increase in fungal diseases Increase Al and Mn to toxic levels Image from CIMMYT, Int. Images from Creative Commons

46 Factors that contribute to acidification Coarse soils Higher precipitation No-till (less subsoil mixing) Excess N fertilization Low organic matter Stubble or hay removal CRP and pea-wheat low N 100 lb N/acre 0.06 ph units Cont wheat high N Engel, Ewing, Miller unpub data

47 Liming to increase soil ph Know: Current soil ph and desired ph Specifics about the lime source Desired crop Rate: from soil test lab or calculate See Soil Acidification Soil Scoops. Rick Engel is developing MT specific recommendations Image: Oregon State University

48 Balanced fertilization extends liming benefit in mixed dryland brome hay Started in 1980, annual spring surface broadcast 100 lb N/ac as AN and 9.8 lb S/ac as sulfate. Surface granular lime in 1992 to soil ph 7. Malhi et al., 2011, SK No diff in soil ph below 2 depth

49 Balanced fertilization increases yield in mixed dryland brome hay Started in 1980, annual spring surface broadcast 100 lb N/ac as AN and 9.8 lb S/ac as sulfate. Surface granular lime in 1992 to soil ph 7. Malhi et al., 2011, SK N alone reduced brome, NS increased brome in stand, bluegrass/fescue grasses did the reverse

50 Select plants suitable to your soil s ph Crop Preferred ph Sweet pea 7-8 Blueberry Raspberry Burr clover > 7 Alfalfa > 5.7 Blue grama grass > 7 White clover < 7 You grow blueberries, the Gallatin Valley grows sweet peas! Select species suitable for ph and soil type, see: Dryland Pastures in MT and WY If soil acidifies over time, pasture species composition will change (Malhi et al., 2011, SK)

51 Questions? On to cation exchange capacity CEC and soil organic matter SOM

52 Cation Exchange Capacity CEC the parking spaces for nutrients in the soil CEC is the total neg. charge on a soil A high CEC soil (> 15) has the capacity to attract and hold nutrients with positive charges, e.g., K +, Zn +2, NH 4 + Soils with large surface areas, such as clay and SOM, have more CEC and therefore are generally more fertile. What else might high CEC soils hold onto? Herbicides

53 Management influenced by CEC and texture Water low CEC soils short frequent irrigation (daily) to avoid leaching nutrients high CEC soils tend to be clay, slow irrigation less often (e.g., low flow emitters, every 3-4 days) Nutrients low CEC soil, a little at a time to avoid leaching loss High CEC, incorporate them to avoid runoff and get to plant roots

54 SOM = Soil organic matter What does SOM NOT do for soil? Response Counter 17% 17% 17% 17% 17% 17% A. Increase CEC B. Provide nutrients as it decomposes C. Hold water which helps nutrients move from soil to plant roots D. Consistently reduce soil ph E. Reduce soil compaction F. Increase water infiltration High surface area and CEC (215 meq/100 g for SOM vs. 58 for clay)

55 Changing SOM We can t change CEC of mineral soil or soil ph very well, but can increase SOM to influence soil CEC Guesses on how long to increase SOM in top foot from 1.4% up to 1.5%? SOM can change: relatively rapidly in a garden we gardeners love to add organic matter takes a long time on cropland/pasture MSU study, CRP (ungrazed, unharvested alfalfa) increased from 1.4% SOM to 1.48% SOM in 10 years in top foot. If you harvest hay, or graze pasture you are maybe maintaining, most likely losing SOM

56 Questions? On to visual and tissue assessment

57 Evaluate soil nutrient status in addition to soil test Visual assessment of tissue: may identify what has been lacking to this point, once symptoms appear, yield may already be compromised. Examples posted at ility/nutrientdeficiencies.html Tissue concentrations, not an exact science either Image by Dairy NZ

58 Visual tissue assessment MOBILE NUTRIENTS lower leaves first Older/lower leaves affected NO Next page YES Effects mostly generalized; plants dark or light green YES NO Effects mostly localized; chlorosis with or w/out spotting YES Plants dark green, often becoming purple or red YES PHOSPHORUS (P) NO Interveinal chlorosis; leaves sometimes red or with dead spots YES MAGNESIUM(Mg) NO Cl Mo Plants light green with leaves light green or yellow; no necrotic spotting YES NITROGEN (N) NO No interveinal chlorosis; chlorotic areas with a burning or spotting along leaf margins YES POTASSIUM (K) NO Mg P K N Plants light green; necrotic spotting on leaves; pale leaves sometimes scorched, cupped or rolled YES MOLYBDENUM (Mo) No interveinal chlorosis; distinct chlorotic and necrotic lesions (spotting) with abrupt boundary between dead and alive tissue YES CHLORIDE (Cl) U of Arizona In Nutrient Management Module 9

59 IMMOBILE NUTRIENTS B Ca S Fe Mn Cu Zn U of Arizona Newer or younger leaves Growing point (terminal bud) dies Leaves of terminal bud become light green at bases; leaves become twisted and brittle and die back at growing point; chlorosis of young leaves YES BORON (B) Young leaves of terminal bud hooked at first, finally turning brown and dying YES CALCIUM (Ca) YES NO Dark green zone next to blunted necrotic leaf tip, thickened curling leaves YES NICKEL (Ni) NO NO Chlorosis w/out interveinal chlorosis Leaves light green; typically no chlorotic spotting or striping YES Chlorosis of young leaves; tips appear withered and will eventually die YES YES YES SULFUR (S) COPPER (Cu) Growing point typically stays alive NO NO YES IRON (Fe) YES NO No sharp distinction between veins and chlorotic areas; spotty appearance YES Young leaves with interveinal chlorosis Sharp distinction between veins and chlorotic areas MANGANESE (Mn) NO Middle leaves with interveinal chlorosis; stunted growth YES ZINC (Zn) (Initially in middle leaves, young and/or old leaves become chlorotic in later stages of deficiency)

60 What is/was deficient here? 33% 33% 33% A. Ability to spell B. Time to read the bag label C. Shouldn t have handed the dog the spreader ID of problem is not always clear cut Response Counter

61 Evaluate and adjust Indicators of soil nutrients: yield, quality (taste, appearance, forage nitrate, grain protein), nutrient deficiencies or toxicities Use this year s observations to fine tune rates next year What else might be unique to your operation to consider that isn t on a soil test? Depth to water table, other? What other tools?

62 Summary Understanding soil properties guides proper fertilization Soil testing is an important tool to calculate fertilizer rates, maximize plant heath, protect environment The right source, rate and timing leads to optimal fertilizer use and plant health. Observe and adjust to your specific conditions

63 Resources On soil fertility website under Extension Publications Soil Nutrient Management for Forages: N (EB0217) Soil Nutrient Management for Forages: PKSMicros (EB0216) Home Garden Soil Testing & Fertilizer Guidelines (MT200705AG) Soil Sampling Strategies (MT200803AG) Interpretation of Soil Test Reports for Agriculture (MT200702AG) Developing Fertilizer Recommendations for Agriculture (MT200703AG) Soil Sampling and Laboratory Selection (4449-1) The Soil Scoop

64 QUESTIONS?